This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to 99102036.3 filed in Europe on Feb. 1, 1999; the entire content of which is hereby incorporated by reference.
The present invention relates to communication station, e.g. a mobile station and in particular to a mobile telephone used for performing speech and data communication in a mobile radio communication network. The mobile radio communication network, in which said mobile station or telephone can be used, can e.g. be constituted by a GSM-network. The mobile station or telephone can also belong to a mobile communication network used at home or in an office allowing a free movement of the user. In particular, the invention relates to the construction of the mobile station, i.e. a mobile telephone allowing the use of the same functionalities with a plurality of different designs for the housing. The invention can be applied to all mobile communication units, e.g. mobile stations including mobile telephones and cordless telephones (e.g. DECT), and also other communication stations, e.g. fixed network cable telephone units.
A mobile station or telephone with which speech and/or data communications can be carried out in a mobile radio communication network typically comprises a power supply unit, an electronic circuit board, on which the electronic components and chips are mounted, which are necessary for providing functions of the mobile telephone, a microphone unit, a loudspeaker unit, a keypad unit, a display unit, an antenna unit, a shielding unit and a card reader unit. Furthermore, there may be provided light emitting diodes (LEDs) which are used for indicating a stand-by operation mode or other operation modes of the mobile telephone and which are also used for illumination e.g. of the keypad. The mobile telephone also comprises a socket which can be connected with a charging device in order to charge a battery of the power supply unit, which is typically inserted in a power supply unit compartment provided on the back surface of the mobile telephone. The card reader unit is typically provided within the mobile telephone underneath the battery pack. Nowadays, typical mobile telephone, e.g. used in a GSM-network, also comprises a system connector for connecting the mobile telephone to other external devices, e.g. a laptop computer.
Typically, when a new mobile telephone providing new or enhanced functionalities has been developed, the mobile telephone is provided with a new (e.g. more modernized) design or outer appearance, in order to distinguish the new mobile telephone from the previous type of mobile telephone, in particular to distinguish the mobile telephone from mobile telephones produced by other manufacturers.
Once the shape and the design of the mobile telephone has been determined by the designer in close collaboration with the engineers which may impose certain restrictions on the outer appearance, e.g. the location of the antenna unit and/or the loudspeaker unit and/or the microphone unit and/or the display unit and/or the requested shape of internal shielding and/or the positioning and arrangement of the keypad (i.e. the switches of the keypad) on the electronic circuit board, the electrical units of the mobile telephone are arranged in order to suit the determined design.
Typically, some electrical units, e.g. the light emitting diodes and/or the loudspeaker unit and/or the microphone unit and/or the display unit, are mechanically connected to a front housing of the mobile telephone, and the charging device coupling socket is mechanically mounted to the back housing of mobile telephone. The printed circuit board is prepared, and then the electrical components respectively arranged in the front and back housing are connected to the printed circuit board through electrical connectors or wirings. Subsequently, the front and back housings are attached at each other by means of fixing screws or by latch means. In this manner, a new mobile telephone is manufactured by requiring many operation steps, and an electrically and mechanically secured connection between the electrical unit(s) in the respective housings and the printed circuit board must be ensured.
Furthermore, since the arrangement of electrical parts like the shielding, the switches, the display, LEDs etc. provided in the front/back housings and on the circuit board as well as the electrical/mechanical connection therebetween can change quite drastically between an old model and a new model, a separate approval of each type of mobile telephone is required. Thus, the development of a new product requires many time-consuming steps and as a result of this the introduction of a new product in the market may be delayed.
In order to provide the mobile telephone with different outer appearances, some manufacturers provide different front housings including the respective electrical units, such as the loudspeaker unit and/or the LEDs, which housings can be clipped to the same printed circuit board. The customer purchases from the dealer the new front housing, and the dealer or the manufacturer will assemble the new front housing with the printed circuit board, in order to connect the electrical units of the front housing to the electrical units on the printed circuit board and/or to the other electrical units provided elsewhere in the back housing.
U.S. Pat. No. 5,768,370 discloses a portable telephone with a housing allowing a user to provide the telephone with a plurality of outer appearances. An overlying cover is removably attachable to a portion of the telephone housing which includes operating buttons and an indicia panel. By exchanging this cover the outer appearance of the telephone can be changed. Within the housing of the telephone the electrical/mechanical units of the telephone are arranged. Since the electrical/mechanical units are specifically adapted to the shape of housing it is not possible to change the overall appearance of the housing expect for the minor portion covered by the replaceable cover.
WO 97/32423 describes an electronic device, in particular a mobile telephone, having a housing in which all electrical/mechanical units of the telephone are housed. The housing has a housing wall with openings for control elements and/or display elements. To the housing of this telephone an external wall element which at least partially covers the housing wall can be connected. This external wall element has openings which are aligned to the openings in the housing such that the control switches and control elements projecting through the housing can be accessed even when said additional external wall element is attached to the housing. Here the additional external wall element is adapted at least in parts to the shape of the housing such that a completely free change of the outer appearance of the telephone is not possible. Furthermore, only the front appearance of the telephone can be changed, since the external wall element can only be attached to the housing at the front and the shape of the housing comprising the function of shielding at the back side can not be changed.
U.S. Pat. No. 5,146,615 describes a mobile telephone comprising a housing including a front cover and a plurality of interchangeable control panels for selective alternative attachment to the front cover. A circuit board is provided on which a keyboard with a plurality of switches is arranged, said switches comprising an arrangement of two meander-like conductors which are interdigitally arranged. A rubber keypad is arranged between said circuit board and said front cover. By using different front covers respectively having a different numbers of holes for the rubber keypad switches and by using different rubber keypads the outer appearance of the mobile telephone is changed in the portion where the keypad is arranged. However, the position of the rubber keypad switches can not be altered since there is a fixed positional allocation of the rubber keypad switches to the switches formed by the meander-type conductors on the circuit board.
U.S. Pat. No. 5,271,056 describes an electromagnetic interference shielding construction in a radio telephone. A mechanically rigid assembly is provided which comprises essentially two printed circuit boards, a display, a keypad and a loudspeaker. Furthermore, a ground foil is part of the mechanically rigid assembly as well as a power supply unit. Some housing units can be directly connected to the mechanically rigid assembly or can enclose the mechanically rigid assembly. One of the two housings forming a shell unit comprises as an electrical unit the antenna of the communication station.
GB 2 107 523 A discloses a multiple membrane switch where a flat-type switch is composed of a first and second conductor pattern arranged in two different planes. The first conductor pattern comprises spiral conductors and the second conductor pattern comprises essentially circular-type conductors. In the center of the second conductor pattern a hole is provided. For such type of large area flat-type switches the special differently shaped conductor patterns allow to reduce a large over-travel, i.e. when the actuator can still travel after the closing of the contacts. That is, in this prior art document the conductor patterns are specially provided in order to keep the contact even if after closing the switch some movement occurs.
As explained above, since the housings in conventional mobile telephones are not only design parts, but also have mechanically rigidly connected electrical parts, like the shielding, the microphone unit and the speaker unit or the LEDs, the assembly flow is not in one direction and requires many assembly steps. Whilst there is some flexibility in this design by exchanging e.g. the front housing, the user must still see the dealer in order to have the mobile telephone reassembled with the new housing. Furthermore, since the housings have rigidly connected to them some electrical units, the front housing can only be used in connection with the specific printed circuit board and the other electrical/mechanical units arranged in an assembly adapted to the location of the electrical units located in the respective housing. That is, the specific housings with their specific electrical parts can only be used for one type of printed circuit board made by a specific manufacturer for a specific type of mobile telephone.
Furthermore, another reason why the outer appearance can not be changed completely is because there is a fixed allocation of the rubber keypad switches to the switches provided on the electronic circuit board. This is a common problem with all communication stations like a mobile telephone, a fixed network cable telephone or a cableless telephone of a DECT system.
As explained above, conventional communication stations like mobile telephones require complicated manufacturing steps, require a separate approval for each type of mobile telephone, and do not allow the user to flexibly change the outer appearance of the communication station (mobile telephone).
Therefore, the object of the present invention is to provide a communication station which has a structure which allows a flexible variation of its outer appearance and which can be manufactured easily and cost effectively.
The object of the invention is solved by a communication station including a power supply unit, a core unit connectable to said power supply unit and constituted by a mechanically rigid assembly of all electrical units of said communication station, and a shell unit which houses said core unit and comprises no electrical units of said communication station.
Thus, by contrast to prior art communication stations, the idea of the present invention is to divide the mobile telephone into one core unit, which comprises all electrical parts including the shielding in a mechanically rigid assembly, a shell unit which encloses the core unit, and a power supply unit. The mechanically rigid assembly essentially constitutes a communication station which is fully functional, if the power supply unit is connected thereto. Thus, the shell unit can have many different designs and can easily be mounted around the core unit even by the user, since no connection of electrical parts is necessary. Since the core unit comprises all electrical parts including the shielding in a mechanically rigid connection, the core unit can be embodied as a fully self-contained unit which can be separately tested i.e. approved for the type approval.
Furthermore, the object of the invention is also solved by a communication station including a power supply unit, a core unit connectable to said power supply unit and a shell unit which houses said core unit, wherein said core unit comprises an electronic circuit board including a keypad unit, said keypad unit comprises a plurality of switches and said switches are formed by at least two spiral-shaped adjacent conductors on said electronic circuit board and bumps being provided on a dome foil of said keypad unit and being adapted to short-circuit the spiral-shaped conductor at different positions.
Thus, not only the outer design of the front housing of the shell unit can be flexibly changed, but also the key layout on the front housing, i.e. the hole layout in the front housing, can be modified. Thus, independently of the constitution of the core unit and the shell unit, a flexible arrangement of the buttons of a keypad and thus of the holes in the front housing of the shell unit can be achieved.
According to one embodiment of the invention, a power supply unit is accommodated in a power supply unit compartment provided in the back housing and connected to the core unit by an electrical connector. The assembly flow is still in one direction, since the core unit can be sandwiched between the front and back housing, and then the power supply unit can be inserted into the compartment and covered with a battery lid.
According to another embodiment of the invention, the core unit comprises the power supply unit compartment, and the power supply unit is accommodated in this compartment, thus also forming a part of the core unit. This type of core unit can again be sandwiched between the front and back housing.
Further advantageous embodiments and improvements of the invention can be taken from the other dependent claims. Hereinafter, the invention will be described with reference to its advantageous embodiments in connection with the accompanying drawings and the following description. It should, however, be noted that the following description only constitutes what is presently considered to be the best mode of the invention, and that further variations and modifications can be carried out on the basis of the teachings contained therein. In particular, the invention can comprise embodiments which consist of features which have been separately described in the description and/or separately claimed in the claims.